[PATCH] scsi: core: Allow the state change from SDEV_QUIESCE to SDEV_BLOCK

[Dexuan Cui <decui@microsoft.com>]

The APIs scsi_host_block()/scsi_host_unblock() are recently added by:
2bb955840c1d ("scsi: core: add scsi_host_(block,unblock) helper function")
and so far the APIs are only used by:
3d3ca53b1639 ("scsi: aacraid: use scsi_host_(block,unblock) to block I/O")

However, from reading the code, I think the APIs don't really work for
aacraid, because, in the resume path of hibernation, when aac_suspend() ->
scsi_host_block() is called, scsi_device_quiesce() has set the state to
SDEV_QUIESCE, so aac_suspend() -> scsi_host_block() returns -EINVAL.

Fix the issue by allowing the state change.

Fixes: 2bb955840c1d ("scsi: core: add scsi_host_(block,unblock) helper function")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
 drivers/scsi/scsi_lib.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 47835c4b4ee0..06c260f6cdae 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2284,6 +2284,7 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
 		switch (oldstate) {
 		case SDEV_RUNNING:
 		case SDEV_CREATED_BLOCK:
+		case SDEV_QUIESCE:
 		case SDEV_OFFLINE:
 			break;
 		default:
-- 
2.19.1